1. Field of the Invention
The present invention relates generally to a filtration apparatus for separating solid particles from a liquid. More particularly, the invention relates to filtration apparatus for removing particulate contaminants from commercial laundry waste water and to methods for accomplishing the same.
2. State of the Art
State and local governments across the country as well as the federal government have enacted new laws or expanded existing laws to reverse or limit the threat of environmental pollution. These environmental laws are typically directed toward commercial enterprises which create various wastes streams as a by-product of manufacturing products or providing services. The commercial laundry industry and particularly commercial laundromats are specifically affected by environmental laws which limit the amount of suspended solids or particulate contaminants in commercial laundry waste water which can be discharged into the environment. Particulate contaminants in commercial laundry waste water generally consist of lint, hair, dirt and soap scum. To meet the requirements of current environmental laws, the amount of particulate contaminants in commercial laundry waste water must be reduced to an acceptable level before it is discharged into the ground water and/or municipal sewage system.
Co-owned U.S. Pat. No. 5,350,526 discloses a filtration apparatus specifically intended for removing particulate contaminants from commercial laundry waste water. It has at least one porous mesh-like filter bag coupled between an inlet manifold for receiving waste water containing particulate contaminants and an outlet manifold for discharging the particulate contaminants separated from the waste water. The filter bag is agitated by a paddle, so as to prevent the mesh-like material of the filter bag from being clogged. The apparatus is capable of trapping particles as small as 5 microns depending on the filter bag mesh. Those skilled in the art will appreciate that the finer the mesh the more slowly the water will be filtered. One of the challenges in designing a filter for commercial laundry waste water is to be able to accommodate a flow rate of about 12,500 gallons per day.
Co-owned U.S. Pat. No. 5,575,913 discloses a filtration apparatus having a housing, a filter element, an inlet, a first discharge outlet and a second discharge outlet. The housing includes a bottom and an upwardly extending surrounding wall. The filter element is disposed in the housing and spans the surrounding wall with the filter element spaced above the bottom of the housing to define an upper chamber and a lower chamber, and the filter element being angled, preferably 45 degrees from the horizontal, so that one end of the filter element is lower relative to the other end. The inlet is in fluid communication with the upper chamber for receiving waste water containing particulate contaminants. A first discharge outlet is in fluid communication with the lower chamber for discharging filtered waste water. The second discharge outlet is in fluid communication with the upper chamber adjacent the lower end of the filter element for discharging filtered particulate contaminants. Particulate contaminants are removed from the filter element by a water spray. The apparatus is capable of trapping particles about 50 microns in diameter.
The apparatus disclosed in the ""913 patent, while a vast improvement over the prior art, can still be improved. Challenges still remain regarding the build up of solids on the filter element; the removal of lint, hair, and other similar solids from water; water overflow through the filter element; hardening of dried solids within the apparatus; the failure of solids to be drained from the apparatus; and the need for regular human intervention.
It is an object of the invention to provide an improved filtration apparatus and method for separating and removing particulate contaminants from a relatively large continuous flow of laundry waste water for discharge of the filtered waste water into the environment, i.e., ground water and/or municipal sewage system.
It is another object of the invention to provide such a filtration apparatus having a filter element for separating particulate contaminants from laundry waste water in which the separated particulate contaminants can be easily and quickly manually or automatically removed from the apparatus without injuring or removing the filter element.
It is still another object of the invention to provide such a filtration apparatus wherein hair, lint, sand and other collected solids are quickly and efficiently discharged without manual intervention.
It is yet another object of the invention to provide such a filtration device wherein collected solids are kept in a fluid suspension for easy fluid discharge.
It is also an object of the invention to provide such a filtration device wherein water overflow through the filter element is prevented.
It is another object of the invention to provide such a filtration device wherein water used to spray the filter element is conserved.
It is still yet another object of the present invention to provide such a filtration apparatus that is easily and inexpensively manufactured; highly efficient in operation, and which requires little lifetime maintenance.
In accord with these objects which will be discussed in detail below, the filtration apparatus of the present invention includes a housing, a filter element, an inlet, a first discharge outlet and a second discharge outlet. The housing includes a bottom and an upwardly extending surrounding wall. The filter element is disposed in the housing and spans the surrounding wall with the filter element spaced above the bottom of the housing to define an upper chamber and a lower chamber, and the filter element being angled, preferably 45 degrees from the horizontal, so that one end of the filter element is lower relative to the other end. A wall is located at the lower end of the filter element to provide a trough adjacent to the lower chamber to collect water with suspended particles. The inlet is in fluid communication with the upper chamber for receiving waste water containing particulate contaminants. The first discharge outlet is in fluid communication with the lower chamber for discharging filtered waste water. The second discharge outlet is in fluid communication with the trough for discharging filtered particulate contaminants suspended in water. Particulate contaminants are removed from the filter element and drained into the trough by a water spray located above the filter element.
According to the preferred embodiment, the trough discharge outlet is located in the middle of the bottom of the trough and the bottom of the trough is tapered downward to the discharge outlet. An overflow discharge is also located in the trough to prevent water from overflowing above the filter element and floating solids back onto the filter element. The overflow discharge is preferably terminated with a T-fitting so that water is drained from below the surface. The lower chamber is also provided with a second discharge for recycling filtered water to the spraying system.
The filtration unit according to the invention has the capacity to filter larger volume of water more efficiently, and requires little or NO human physical participation. The addition of the trough creates a filter system with its own solid waste storage capabilities. This creates longer filter runs without the need for manual or electrically timed discharge, this means less energy used and less manual attention to the unit.
The filter screen is never compromised with the collected solids on the mesh screen itself Thus the filter screen is always free from solids. This allows the filter the ability to handle a continuous higher volume and will always remain at its maximum use and potential.
The unit will also supply itself with its own feed water for the action of spraying down the screen.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.